We report the synthesis of tungsten oxide (WO3) nanosheets using a simple yet efficient hydrothermal technique free of surfactantand template. The WO3 nano-sheets are self-assembled as well to form ordered one-dimensional chain nanostructure. A comprehensive microscopic characterization reveals that the nano-sheets have triangular and circular two different shape edges, dislocation and stacking faults are also observed, which should have implications for our understanding of catalytic activity of ceria. We also propose a growth mechanism for the nano-sheets. As a result of this unique morphology, this WO3 nano-sheets are found to show excellent gas-sensing properties which can use as promising sensor materials detecting ethanol with low concentration.

Coatings are pre-fabricated on the China low activation martensitic (CLAM) steel via thermal spraying using Cr-Fe-Al-Ti mixed powders. Crystalline and amorphous multiphase ceramic coatings are formed by a new laser surface in situ prefabricated coatings in situ reaction technology under atmospheric environments based on the Standard Gibbs free-energy theory. The grain boundary of incomplete recrystallisation section and perfect crystallisation section can be observed clearly by high-resolution transmission electron microscopy. The Al 2 O 3 and TiO 2 are found to be formed in the crystallisation section. In addition, we adopt a new method to measure bonding strength of coating and base material, and the average shear strength is found to be 290 MPa. Further finite-element analysis shows that the shear stress distribution between the coatings and substrate is consistent with the experimental data. The average microhardness of the coatings is found to reach 1864.19 HV 0.2 .The coatings also exhibit the strongest liquid Pb corrosion resistance. This technique may be important in technological improvement of surfaces of the candidate structural materials for the accelerator-driven sub-critical system, which is usually applied to handle the nuclear waste under extreme conditions.

An Al2O3–TiO2 amorphous composite coating with a thickness of 100–120 μm was fabricated on China low activation martensitic steel (CLAM steel) by oxygen acetylene flame spraying technology and the laser in-situ reaction method. We investigated the microstructures and mechanical properties of the coating after liquid lead-bismuth eutectic (LBE) alloy corrosion under different temperatures for 300 h and found that the corrosion temperature of the LBE had no observable effect on the microstructure and chemical phase of the Al2O3–TiO2 amorphous composite coatings. However, the mechanical properties (micro-hardness and shear strength) of the Al2O3–TiO2 multiphase coating deteriorated slightly with the increase in the immersion temperature of the LBE. As a result of oxygen acetylene flame spraying and laser in-situ reaction technology, it was found that the Al2O3–TiO2 amorphous composite coating exhibits an excellent LBE corrosion resistance, which is a candidate structural material for the accelerator-driven subcritical system (ADS) to handle nuclear waste under extreme conditions.

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The chromium coating prepared by multi-arc ion plating on the surface of zirconium alloy is easy to fall off under extremely harsh conditions due to the defects of larger particles, pores and weak adhesion between the coating and the zirconium alloy substrate. Here we apply a new composite process for the fabrication of Cr coating by laser melting multi-arc ion plating technology. The numerical model of temperature field laser melting treatment was established, and based on the analysis of the above temperature field of laser melting treatment, the laser with an energy density of 9 × 104 J/cm2–18 × 104 J/cm2 was selected as the heat source. Laser energy density has a great influence on the diffusion behavior of Cr at the coating-substrate interface. When the energy density of laser is 9 × 104 J/cm2, the laser heat source cannot provide enough energy to melt the surface of the coating, however, the Cr element diffuses slightly at the membrane base interface, forming a Cr diffusion zone of about 4 μm. When the energy density of the laser increases to 13.5 × 104 J/cm2, the Zr element of the substrate diffused to the whole Cr coating, and the original Cr coating disappeared, forming a Zr-Cr diffusion and fusion zone of 30 μm. As the laser preparation process of the coating is a mixed sintering process of liquid phase sintering and solid phase sintering, the coating surface forms a dense zone and a loose zone respectively, resulting in the increase of porosity and particle rate. With the laser energy density increasing gradually, the Zr-Cr fusion zone is formed, and the coating surface particles were gradually refined and the pores were significantly reduced. With the further increase of laser energy density of 18 × 104 J/cm2, the Zr-Cr fusion zone was extended to 60 μm, and the porosity and particle rate were reduced to 0.3% and 0.4% respectively. In addition, the original stratification cracking of the film base at the fracture of the tensile specimen disappears, and the protrusion of the interface is formed. Coatings with dimple fractures were found, which indicates that the coating exhibited ductility and interfacial metallurgical bonding.